FIELD OF THE INVENTION
The present invention relates to a seat belt system for protecting
a passenger on a mobile unit including an automotive vehicle according to the preamble
of claim 1. More particularly, the present invention relates to an air belt system
wherein a part of the seat belt is in a shape of an envelope and inflatable with
gas from a gas generator. More particularly, the present invention relates to an
air belt system wherein gases are supplied from a buckle through a tongue into
DESCRIPTION OF RELATED ART
The closest prior art document US-A-5,465,999 discloses an inflatable
seat belt apparatus, which is formed of an inflatable portion, which is usually
maintained in a band shape. A coupling tongue with a gas passage can be engaged
with a buckle, in which housing a gas generator is provided. When the tongue pipe
is coupled to a coupling hole of the buckle body, a tongue pipe releasing ring
is pressed against a biasing force of a spring by the tongue pipe distal end in
a direction away from the tongue.
Fig. 7a is a general perspective view of an air belt system disclosed
in Japanese Patent Publication 5-85301A. Fig. 7b is a cross sectional view taken
along the line B-B of Fig. 7a.
An air belt system 1 has a shoulder belt 2 extending diagonally across
a passenger from a right side to a left side thereof, a lap belt 3 extending from
the right side to the left side of the passenger, a buckle unit 4 disposed on a
floor of a vehicle body or the like, a tongue 5 for being inserted into and engaged
with the buckle unit 4 when the belt is to be fastened, and an intermediate guide
6 for guiding the shoulder belt 2.
The shoulder belt 2 comprises a normal belt 2a which is of the same
material as that for generally used conventional seat belts and an inflatable belt
2b connected to one end of the normal belt 2a. The normal belt 2a is slidably drawn
through the intermediate guide 6. The other end of the belt 2a is coupled to a
seat belt retractor (ELR) 7 having a collision lock feature fixed to the vehicle
body. The seat belt retractor 7 is adapted to wind up the normal belt 2a.
The belt 2b is so located as to be in contact with the passenger,
and the tongue 5 is secured to the end thereof opposite the normal belt 2a.
The lap belt 3 is made of a normal webbing which is of the same material
as generally used seat belts and coupled to the tongue 5 on one end and to a seat
belt retractor (ELR) 8 fixed to the vehicle body on the other end. The buckle unit
4 further includes a gas generator 9 coupled thereto, which actuates and generates
high pressure gas in case of emergency such as collisions.
The tongue 5 and the buckle unit 4 are provided with passages for
allowing the gas to pass from the gas generator 9 to the inflatable belt 2b.
The inflatable belt 2b of the shoulder belt 2 is maintained in a shape
of a webbing in normal state by folding a belt body 2c as shown in solid line in
Fig. 7b and covered for example by a knitted fabric 2d and sewed on both sides
thereof. When the gas generator 9 is actuated, a sewed portion 2e of the knitted
fabric 2d comes off with ease by the force of inflation of the shoulder belt 2
to allow the pouched belt 2b to inflate and deploy as shown in a phantom line.
OBJECT AND SUMMARY OF THE INVENTION
A first object of the present invention is to introduce gases surely
from a gas passage of a buckle into a gas passage of a tongue of an air belt system.
A second object of the present invention is to provide the air belt
system wherein an unusual noise generated when the automotive vehicle is subject
to vibration or the like is reduced.
A third object of the present invention is to provide the air belt
system wherein foreign materials are prevented from being introduced into the gas
passage of the buckle.
The air belt system in the present invention has an air belt which
inflates with gas introduced therein, a tongue connected to one end of said air
belt, a buckle for being engaged with the tongue, gas passages provided in the
buckle and in the tongue respectively, and a gas generator for supplying gas to
the gas passage of the buckle. The buckle has a slidably mounted cylindrical piston
having a gas passage therein and advancing by means of the pressure of gas. The
tongue is provided with an opening where the piston is inserted when being advanced.
In the air belt system of the invention, actuation of the gas generator
advances and inserts the piston into a duct of the buckle to allow gas from the
piston to be introduced into the gas passage in the buckle.
According to an embodiment of the present invention, the buckle may
be provided with a cylindrical piston holder fitted around the piston, and the
piston may be provided with a seal ring sliding with respect to the inner surface
of the piston holder.
According to the embodiment of the air belt system of the present
invention, the seal ring prevents the gas leakage and noise generated when the
piston hits against the piston holder.
In this embodiment, it is preferable that the diameter of the piston
is small in the front side and large in the back side to form a shoulder therebetween
where the seal ring is seated, and on the tip portion of said piston holder, there
an inwardly facing flange to stop the piston via seal ring on the large-diameter
portion when the piston is advanced. The large-diameter portion of the piston
hits against the flange via the seal ring, and consequently the noise occurred
by such hits is reduced.
In the present invention, a cap which is opened by the pressure of
the gas may be provided integrally on the tip of the piston. The tip portion of
the piston is sealed with the cap even when the tongue is not engaged with the
buckle so that foreign materials (such as dust or sand) cannot come into the gas
passage in the piston or the buckle. The cap formed integrally with the piston
prevents the cap from coming apart when the pressure of gas is introduced into
the piston to ensure the advancement of the piston to the extremity. When the piston
arrives at its extremity, a strong force caused by the pressure of gas is applied
against the inner surface of the cap to release the cap.
It is preferable that the inner surface of the cap is provided with
linear grooves which are to be ripped by the pressure of gas and divided into a
plurality of flaps. The flaps on the cap generated by such rips prevent gas from
leaking when gas flows from the piston to the gas passage in the tongue.
The cap is preferably doming out. The cap having such a configuration
can hardly be deformed by the force applied from the outside.
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
- Fig. 1a is a front view illustrating a tongue and a buckle of the air belt
system in an embodiment of this invention, and Fig. 1b is a perspective view of
the buckle thereof;
- Fig. 2 is a constitutional view of buckle and the tongue in Fig. 1;
- Figs. 3a, 3b, and 3c are cross sectional views illustrating the coupling states
of the buckle and the tongue in Fig. 1;
- Fig. 4a is a perspective view of the piston, Fig. 4b is a side view of the
piston, Fig. 4c is a cross sectional view of the piston, Fig. 4d is a bottom view
of the piston and Fig. 4e is an enlarged view of the part E in Fig. 4c;
- Fig. 5 is a bottom view of the piston in another configuration.
- Fig. 6 is a bottom view of the piston in still another configuration; and
- Fig. 7a is a general perspective view and Fig 7b is a cross sectional view
of an air belt in the related art.
Referring to the drawings, embodiments of the present invention will
be described in further detail. Fig. 1a is a front view illustrating a tongue and
a buckle of an air belt system in an embodiment of this invention. Fig. 2 is a
constitutional view of the buckle and tongue of this embodiment illustrating the
state where they are engaged with each other and the outer shell is removed. Fig.
3 is a enlarged cross section of the tongue and buckle illustrating the coupled
portion thereof. Fig. 4 illustrates the constitution of the piston.
The air belt system in the present invention has a tongue 10, a buckle
12 for receiving said tongue 10, and a gas generator (inflator) 16 or the like
for supplying gas to said buckle 12. The tongue 10 has a tongue base 18 having
a gas passage (duct) 20, a tongue plate 24 connected to the tongue base 18 with
a connecting pin 22, and a lap belt anchor (not illustrated). The interior of the
duct 20 is in communication with the interior of the air belt 14.
The tongue plate 24 is inserted into the opening 34 (Fig. 1b) provided
on the buckle 12, and latched with a latch lug formed on the latch mechanism 28
in the buckle 12 fitted into a latch aperture 26. By pressing down a press button
30 provided on the buckle 12, the latch is released and the tongue plate 24 is
pressed out of the buckle 12 under action of the spring (not illustrated). Numeral
32 represents a tongue engagement sensing switch for sensing when the tongue plate
24 is inserted deeply enough into the buckle 12 and is engaged completely.
To the lap belt anchor, the tip portion of the lap belt is connected.
The seat belt retractor is adapted to wind up the back end side of the lap belt
as shown in Fig. 7.
In this embodiment, the air belt 14 constitutes a part of the shoulder
belt, and the back end side of the air belt 14 is connected to the tip of the
webbing constituting the shoulder belt, and the back end of the webbing can be
retracted into the seat belt retractor for the shoulder belt.
On the tip surface of the buckle 12, there is provided an opening
34 for the tongue plate and a piston 60 projectably mounted thereon.
As shown in Fig. 2, a gas passage (duct) 46 made of a pipe is connected
via an attachment 44 to a gas nozzle 42 on the tip of the inflator 16, and a base
end of a piston holder 50 is fixed to the tip of the duct 46. The piston holder
50 is generally cylindrical and having an inwardly facing flange 52 on the tip
The piston 60 is generally cylindrical and a back portion 62 thereof
is large in diameter and a front portion 64 thereof is small in diameter. The
small-diameter portion 64 is inserted through the flange 52 of the piston holder
50. The large-diameter portion 62 is so formed as to be too large in diameter to
pass through the flange 52. The tip surface of the piston 60 is closed with the
cover cap 66. On this cover cap 66, there are provided tear lines 68 (Figs. 3a,
3b) formed of a shallow grooves, and when the pressure of gas is applied from the
inflator 16, the cover cap 66 is ripped along the tear lines 68 and divided into
a plurality of strips or flaps 70 (Fig. 3c).
In the present embodiments, tear lines 68 extend radially from the
center of the cap 66 in three directions (allowing 120° distances in circumferential
This cap 66 is formed for example, of aluminum, aluminum alloy, magnesium
alloy, heat resistant synthetic resin, etc., in one piece with the piston 60 so
that the cap 66 does not come apart from the piston 60 even when the pressure of
gas is applied.
The cap 66 is outwardly doming out so as not to be deformed even
when the force is applied from the outside.
On the small-diameter portion 64 of the piston 60 is fitted with an
O-ring 72 as a seal ring. The O-ring 72 is disposed on the shoulder between the
small-diameter portion 64 and the large diameter portion 62.
As shown in Fig. 2 and Fig. 3a, with the tongue 10 engaged within
the buckle 12, the tip portion of the piston 60 is opposed to the entrance of the
When the inflator 16 is actuated and the piston 60 is advanced to
its extremity by the pressure of gas, the tip of the piston 60 is placed into the
duct 20 as shown in Fig. 3b.
In the case where the cover cap 66 is ripped with the tip of the piston
60 inserted into the duct 20 as shown in Fig. 3c, the tips of generated flaps 70
enter into the duct 20.
A bracket 80 is projected downwardly from the buckle 12 so that it
may be fixed to the member (not illustrated) of the vehicle body via a bolthole
formed on the bracket 80.
In this arrangement of the air belt system, a tongue 10 is engaged
with the buckle as shown in Fig. 2. In this case, the tongue plate 24 is inserted
into the opening 34 and latched by the latch mechanism 28 as described above, and
the tip of the piston 60 is opposed to the gas inlet port of the duct 20 as shown
in Fig. 3a.
When the inflator (gas generator) 16 is actuated with the tongue
engaged, gas is supplied through the duct 46 into the piston 60 to push the piston
60 up. The piston 60 advances until the large-diameter portion 62 touches via O-ring
72 to the flange 52. The cover 66 is then ripped to allow gas to flow through the
duct 20 into the air belt 14 to inflate the air belt 14.
In this embodiment, since the tips of the flaps 70 enter into the
duct 20 as shown in Fig. 3c, and the space between the duct 20 and the piston 60
is surrounded by the flaps 70, gas may be supplied through the duct 20 to the air
belt 14 with no or little leakage to the outside thereof.
In this embodiment, O-ring 72 fitted on the piston 60 is in elastic
contact with the outer surface of the piston 60 and the inner surface of the piston
holder so as to prevent gas leakage, as well as an unusual noise which may occur
by the hitting of the piston 60 against the piston holder 50 even when the buckle
12 is subjected to vibration under the state shown in Fig. 2 and Fig. 3a.
When the piston 60 advances to its extremity and the large-diameter
portion 62 hits against the flange 52 as shown in Fig. 2b, the shock caused by
the hits of the large-diameter portion 62 against the flange 52 is eliminated
due to the presence of the O-ring between the large diameter portion 62 and the
flange 52 to prevent components from being damaged.
In the buckle 12 of this embodiment, when the tongue 10 is engaged,
the exit of the piston is closed by the cover 66. Therefore the entrance of foreign
materials into the piston 60 and the duct 46 is prevented. Since the entrance of
foreign materials into the piston 60 and the duct 46 is prevented in this way,
the entrance thereof with gas into the air belt 14 when the air belt system is
actuated may also be prevented.
In the embodiment described above, the tear lines extend radially
from the center in three directions. However, they may extend in four directions
as the tear lines 68Ain Fig. 5, or may extend even in five directions. Though the
tear lines 68 and 68A are arranged to form triangle flaps 70 and 70A in Fig. 4
and Fig. 5, the tear line 68B may be arranged so as to form a trapezoidal flaps
70B and 70B, and triangle flaps 70C and 70C.
As described hitherto, the present invention provides an air belt
system which ensures gas flow from the buckle side to the tongue side, and prevents
an unusual noise from occurring. In addition, the entrance of foreign materials
into the gas passage on the buckle side or into the piston is prevented.